Particulate filter behaviour of a Diesel engine fueled with biodiesel

Biodiesel is an alternative and renewable fuel made from plant and animal fat or cooked oil through a transesterification process to produce a short chain ester (generally methyl ester). Biodiesel fuels have been worldwide studied in Diesel engines and they were found to be compatible in blends with Diesel fuel to well operate in modern Common Rail engines. Also throughout the world the diffusion of biofuels is being promoted in order to reduce greenhouse gas emissions and the environmental impact of transport, and to increase security of supply. To meet the current exhaust emission regulations, after-treatment devices are necessary; in particular Diesel Particulate Filters (DPFs) are essential to reduce particulate emissions of Diesel engines. A critical requirement for the implementation of DPF on a modern Biodiesel powered engine is the determination of Break-even Temperature (BET) which is defined as the temperature at which particulate deposition on the filter is balanced by particulate oxidation on the filter. To fit within the exhaust temperature range of the exhaust line and to require a minimum of active regeneration during the engine running, the BET needs to occur at sufficiently low temperatures. In this paper, the results of an experimental campaign on a modern, electronic controlled fuel injection Diesel engine are shown. The engine was fuelled either with petroleum ultralow sulphur fuel or with Biodiesel: BET was evaluated for both fuels. Results show that on average, the BET is lower for biodiesel than for diesel fuel. The final goal was to characterize the regeneration process of the DPF device depending on the adopted fuel, taking into account the different combustion process and the different nature of the particulate matter. Overall the results suggest significant benefits for the use of biodiesel in engines equipped with DPFs.